This invention relates to electromechanical timers used in controlling appliance functions where a selection of timer functions can be made by manually rotating a control knob on the timer. Electromechanical timers are widely used to control functions in automatic appliances. Such timers use a control knob to select various functions desired to be performed by the timer. Generally the control knob is fixed on a shaft that provides the rotational axis for a rotating cam. If the a timer shaft is rotated in a direction counter to its normal rotation or wrong direction, the improper rotation may cause damage to the timer's switch contacts, damage to the timer's drive means, and damage to the appliance by abrupt function changes.
In prior art timers, control knob rotation in the improper direction is prevented by attaching the control knob to the shaft with a threaded connection. If the user rotates the control knob in the wrong direction, the knob will unscrew from the shaft and the camstack will remain stationary.